Acid Gun
Shoots particles that corrode soft and medium materials.
Press t to toggle between remembering the transform. You can use this watch the acid coming from a different angle. (when pressed it remembers the current position and facing of the acid gun and uses this static position to fire until pressing t again)
Press M for options in game.
Acid gun with voxels is a different version of the same mod which uses voxels instead of particles (voxels have more physics and are worse for frames.)
Check out Acid Proof-of-Concept for a different take on acids